Pulmonary fibrosis or idiopathic pulmonary fibrosis (IPF) is a disease of unknown cause, characterized by chronically progressive fibrosis of mesopulmonum. The occurrence of the above disease is mainly limited to lungs, showing signs of a histologically pathognomonic usual interstitial pneumonia (UIP). A prevalence rate of pulmonary fibrosis varies among reports, but is known to be 2-29 people per 100,000 of the population and is designated as a rare incurable disease in South Korea. Clinical outcomes of the IPF vary widely, wherein the IPF is a critical disease which generally progresses into a respiratory failure due to a slowly progressive pulmonary function insufficiency and in which an average time of survival after diagnosis is within 2-3 years. For that reason, many attempts have been made to find an exact cause and etiological factor of the IPF and develop a medicine accordingly, but there has been no proper medicine so far.
Also, radiation treatment is one of the main treatment modalities in lung cancer, contributing to both its cure and palliation in localized and advanced disease, respectively. However, about 70-80% of all the lung cancer patients who receive the radiation treatment suffer from mild or severe side effects on their lung organs. Pulmonary fibrosis, one of the representative side effects resulting from the radiation treatment, brings about a functional loss of lung organs and reduces a lung capacity of patients, thus having a negative effect on their quality of life and leading to even death. However, due to a lack of effective drugs to prevent or reduce a state of such disease, both pneumonia and pulmonary fibrosis caused after irradiating lungs are a serious problem that have to be urgently solved.
In particular, for the pulmonary fibrosis resulting from the existing radiation treatment, efforts have been made to reduce its side effects only by administering steroid later upon the outbreak of radiation pneumonia, which occurs in its previous stage of fibrosis. However, there has been no substantial medicine for radiation-induced pulmonary fibrosis. Steroid therapy also has many side effects, thus having a limit on administration for a long period of time.
The heat shock protein 27 (HSP27) was originally known as a representative chaperone protein, promoting carcinogenesis as a low molecular weight chaperone protein and causing cancer resistance, but also has been recently known to be involved in a tissue fibrosis process.
Against this backdrop, it is urgent to find a medicine for pulmonary fibrosis, in particular, for radiation-induced pulmonary fibrosis.